1. Technical Field
The present invention relates to disk refiners and more particularly to improvements in refiner plates and mounting assemblies therefore.
2. Description of the Related Art
Disk refiners are used in the paper manufacturing industry to prepare the cellulose fibers of a paper pulp into a desired condition prior to delivering the pulp to the papermaking machine. Double disk refiners, such as described in U.S. Pat. No. 4,083,503, have refiner plates attached to a rotating disk, or rotor, and complementary refiner plates attached to an opposing, non-rotating disk, or stator. Multiple disk refiners, such as described in U.S. Pat. No. 4,783,014, have a plurality of rotatable and non-rotatable refiner plates interleaved within a refining chamber of the refiner. Counter-rotating disk refiners, such as described in U.S. Pat. No. 4,129,263, have two counter-rotating refining disks each mounted to its own motor-driven shaft.
There are many different disk refiners of differing configurations and diameters. There are also many different types of refiner plates. One type of a refiner plate is a complete annular plate which is cast or otherwise manufactured as  a one-piece member. A major disadvantage of complete annular refining plates is the high cost of fabrication, and difficulties associated with the transport and installation of such a large, heavy component. These issues are avoided by a refiner plate which comprises a plurality of individual segments which cooperatively form an annular plate when fitted together. U.S. Pat. Nos. 4,039,154 and 5,425,508 provide examples refiner plates having a plurality of individual segments, which are assembled to form a complete annular plate.
Moreover, refiner plates have a working refining surface that is typically formed by a plurality of spaced apart, raised, rib-like projections, generally called “bars”. There are many refiner plate patterns which are well-known within the paper industry. The bars and other portions of the working surface are gradually abraded or worn away from use, and are subject to damage from excessive loading, such that they require replacement periodically. Thus, another advantage in using segmented refiner plates pertains to replacement of worn or damaged bars. Replacing an entire annular refiner plate due to wear or damage in a discrete part of the refiner plate is inefficient and costly compared to replacing only the segment or segments that are worn or damaged.
Furthermore, regardless of the refiner plate type or bar pattern, the mounting arrangement can vary by refiner manufacturer, and even a single refiner manufacturer may utilize different plate mounting arrangements in terms of the number, size and spacing of the mounting bolts, especially when the overall size of the plates vary considerably. Consequently, a refiner plate manufacturer supplying refiner plates for several manufacturer's refiners have been required to manufacture numerous different refiner plates of the same diameter to be used in the many different disk refiners, even if the same bar configuration is used.
This latter situation can be improved by using an adapter to mount the refiner segments. U.S. Pat. No. 5,934,585, assigned to the assignee of the present invention, and hereby incorporated be reference herein, provides an example of mounting assembly in which an adapter has holes that match the standard bolt pattern of the refiner disk. Refiner segments then mount to the adapter using a  clamping ring. Since only the adapter bolts to the refiner disk, and since the adapters are not wear parts, for any given bar pattern refiner manufacturers can supply a single replacement refiner segment type for different disk refiners.
Additionally, while the refiner plate bars can be sized and aligned in many different ways, they generally narrow in the radial outward direction to facilitate courser to finer refining of the pulp and are also aligned in some way that facilitates flow of the pulp between the bars toward the outer periphery of the refiner plate. One additional issue with existing refiner plates, is that it is inefficient to refine pulp, for example at finer bars located in a radially outer region of the refiner segment, that has already been sufficiently refined to an acceptable size. U.S. Pat. No. 7,347,392, which is also assigned to the assignee of the present invention, and hereby incorporated as though fully set forth herein, provides an example of refiner plates that have internal flow channels through which steam and “accepts” can be carried away from the refining surface between the refiner plates so that they are not refined further. While this provides a significant improvement in efficiency when compared to conventional large refiner segments, it complicates the manufacturing process. Sand casting, a less accurate and more costly technique, is used to create sand core in the casting mold that forms the internal flow channels in the segment. This can lead to imperfections or defects in the cast refiner segment as a result of the release gas into the molten steel as the sand is burned off during the casting process.